This invention relates to paint ball guns of the type usually used in recreational activities. More directly, the invention relates to a gun barrel with an adjustable diameter for use in projecting paint ball pellets with a compressed gas.
Paint ball guns are generally used for target shooting or for recreation where individuals, or teams, fire paint balls or pellets at each other in an effort to simulate combat, or war. In operation, a paint ball is deposited into a compression chamber of the paint ball gun. By pulling the trigger on the gun, the user unleashes a short blast of compressed gas (generally carbon dioxide) that propels the paint pellet out of the compression chamber, through the barrel of the gun, and out of the muzzle. To maximize the force of the compressed gas on the paint ball, the bore of the barrel of the paint ball gun should slightly compress or be close in diameter to the diameter of the paint pellet. However, a barrel with a bore that is too small for the paint pellet will require extra energy to dislodge the pellet from the barrel slowing it down or in extreme circumstances, causing it to become lodged in the barrel or causing the pellet to break apart while traveling down the barrel. Conversely, a barrel with a bore much larger than the paint pellet will allow the compressed gas to leak around it, reducing the force of the gas upon the pellet, resulting in a slower muzzle velocity and less range.
Paint pellets are produced by many different manufacturers and vary in their spherical diameters. As traditional paint ball guns have a barrel that is not adjustable, some paint pellets may not fire effectively because of the differing spherical diameters.
It has been known to compensate for spherical deviation of paint pellets by using removable barrels that can be replaced with barrels of differing bore sizes. This is achieved, in the prior art, by the addition of a quick disconnection mechanism. Such a paint ball gun barrel is disclosed in U.S. Pat. No. 6,273,080 to D. Sullivan, Jr. incorporated herein by reference. A quick disconnect barrel system, however, requires the user to carry numerous barrels of differing bore diameters to ensure availability of a bore properly matching the size of the paint pellets to be fired.
It has also been known to use interchangeable bore sleeves of varying diameter or to use pins with a spring loaded tension to position the paint pellet in the barrel of the gun. The pins are placed around the interior of the barrel at 3 or 4 locations. However, as the pins provide only point contact, compressed gas may be lost around the paint pellet by traveling between the pellet and the inner wall of the barrel.
In one embodiment of the present invention, a barrel for a paint ball gun having an adjustable bore is provided. The barrel includes an adjustment mechanism that compresses an inner-bore sleeve to numerous diameters, allowing the paint ball gun to fire paint pellets of different sizes.
The adjustment mechanism is capable of adjusting the inner diameter of the barrel without having to remove the barrel from the paint ball gun. In one embodiment of the invention, rotation of an outer collar around the barrel is sufficient to alter the diameter of the barrel.
One embodiment of the invention includes a resilient inner-bore sleeve capable of springing back to a larger diameter whenever the compression force is removed. The inner-bore sleeve should be sufficiently resilient to continually return to its initial rest dimensions, thereby ensuring the same maximum barrel diameter may always be achieved by the adjustable bore barrel.
With the present invention, the user is able to accurately set the diameter of the bore without having to carry replacement barrels, attachments, or measuring devices. Any one of numerous well known alignment mechanisms may be used to allow the user to accurately set the diameter of the bore. The alignment mechanisms allow the user to set the bore diameter for more efficient utilization of the compressed air charge of the gun during firing. Furthermore, the alignment mechanisms allow the user to experiment in the use of different types of paint pellets enabling the user to compare various brands and various sizes without the need to purchase additional paint ball guns.